org.apache.hadoop.chukwa.datacollection.adaptor.filetailer

Class LWFTAdaptor

java.lang.Object

org.apache.hadoop.chukwa.datacollection.adaptor.AbstractAdaptor

org.apache.hadoop.chukwa.datacollection.adaptor.filetailer.LWFTAdaptor

All Implemented Interfaces:

Adaptor

Direct Known Subclasses:

FileTailingAdaptor, RCheckFTAdaptor

public class LWFTAdaptor
extends AbstractAdaptor

A base class for file tailing adaptors. Intended to mandate as little policy as possible, and to use as few system resources as possible. If the file does not exist, this class will continue to retry quietly forever and will start tailing if it's eventually created.

Field Summary

Fields

Modifier and Type	Field and Description
static int	DEFAULT_MAX_READ_SIZE This is the maximum amount we'll read from any one file before moving on to the next.
static String	MAX_READ_SIZE_OPT

Constructor Summary

Constructors

Constructor and Description
LWFTAdaptor()

Method Summary

Modifier and Type	Method and Description
String	getCurrentStatus() Return the adaptor's state Should not include class name or byte offset, which are written by caller.
String	getStreamName()
String	parseArgs(String params)
long	shutdown(AdaptorShutdownPolicy shutdownPolicy) Signals this adaptor to come to an orderly stop.
void	start(long offset)
boolean	tailFile()
String	toString()

Methods inherited from class org.apache.hadoop.chukwa.datacollection.adaptor.AbstractAdaptor

deregisterAndStop, getType, hardStop, parseArgs, shutdown, start

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, wait, wait, wait

Field Detail

DEFAULT_MAX_READ_SIZE

public static final int DEFAULT_MAX_READ_SIZE

This is the maximum amount we'll read from any one file before moving on to the next. This way, we get quick response time for other files if one file is growing rapidly.

See Also:

Constant Field Values

MAX_READ_SIZE_OPT

public static final String MAX_READ_SIZE_OPT

See Also:

Constant Field Values

Constructor Detail

LWFTAdaptor

public LWFTAdaptor()

Method Detail

start

public void start(long offset)

Specified by:

start in class AbstractAdaptor

getCurrentStatus

public String getCurrentStatus()

Description copied from interface: Adaptor

Return the adaptor's state Should not include class name or byte offset, which are written by caller. The datatype should, however, be written by this method.

Returns:

the adaptor state as a string

See Also:

Adaptor.getCurrentStatus()

toString

public String toString()

Overrides:

toString in class Object

getStreamName

public String getStreamName()

parseArgs

public String parseArgs(String params)

Specified by:

parseArgs in class AbstractAdaptor

shutdown

public long shutdown(AdaptorShutdownPolicy shutdownPolicy)
              throws AdaptorException

Description copied from interface: Adaptor

Signals this adaptor to come to an orderly stop. The adaptor ought to push out all the data it can before exiting depending of the shutdown policy

Parameters:

shutdownPolicy - is defined as forcefully or gracefully

Returns:

the logical offset at which the adaptor was when the method return

Throws:

AdaptorException - Exception on shutdown

tailFile

public boolean tailFile()
                 throws InterruptedException

Throws:

InterruptedException